A functional fluid is a term which encompasses a variety of fluids including but not limited to tractor fluids, automatic transmission fluids, manual transmission fluids, hydraulic fluids, power steering fluids, fluids related to power train components and fluids which have the ability to act in various different capacities. It should be noted that within each of these fluids such as, for example, automatic transmission fluids, there are a variety of different types of fluids due to the various transmissions having different designs which have led to the need for fluids of markedly different functional characteristics. One type of functional fluid is generally known as a tractor fluid which can be used in connection with various types of tractor equipment in order to provide for the operation of the transmission, gears, bearings, hydraulics, power steering, mechanical power take off and oil immersed brakes of the tractor.
The components included within a functional fluid such as a tractor fluid must be carefully chosen so that the final resulting fluid composition will provide all the necessary characteristics required and pass a variety of different types of tests. In general a tractor fluid must act as a lubricant, a power transfer means and a heat transfer means.
Tractor fluids have a number of important specific characteristics which provide for their ability to operate within tractor equipment. Such characteristics include the ability to provide proper frictional properties for preventing wet brake chatter of oil immersed brakes while simultaneously providing the ability to actuate wet brakes and provide power take-off (PTO) clutch performance. A tractor fluid must provide sufficient antiwear and extreme pressure properties as well as water tolerance/filterability capabilities.
The extreme pressure (EP) properties of tractor fluids are demonstrated by the ability of the fluid to pass a spiral bevel test as well as a straight spur gear test. The tractor fluid must pass wet brake chatter tests as well as provide adequate wet brake capacity when used in oil immersed disk brakes which are comprised of a bronze, graphitic compositions and asbestos. The tractor fluid must demonstrate its ability to provide friction retention for power shift transmission clutches such as those clutches which include graphitic and bronze clutches.
U.S. Pat. No. 4,410,438 discloses a lubricant and liquid fuel composition which includes borated epoxides which are indicated as being useful in fluids such as heat exchange fluids, transmission fluids, and hydraulic fluids.
U.S. Pat. No. 3,933,659 discloses a functional fluid for lubricating oil compositions which is comprised of a major amount of an oil of lubricating viscosity and an effective amount of an additive. The additive includes effective amounts of an alkaline succinimide, a group II metal salt of a dihydrocarbyldithiophosphoric acid, a basic sulfurized alkaline earth metal alkyl phenate and a component which is a fatty acid ester, fatty acid amide or fatty acid amine or mixtures thereof. The patent indicates that the lubricating compositions are useful as functional fluids in systems requiring fluid coupling, hydraulic fluid and/or lubrication of relatively moving parts. The lubricating compositions are indicated as being useful as the functional fluid in automatic transmissions and particularly in the automatic transmissions of passenger automobiles.
U.S. Pat. No. 4,116,877 discloses an elastomer compatible seal swell additive. The additive may be used in connection with automatic transmission, power transmission fluids and hydraulic steering fluids. The fluid is a mineral lubricating base oil which includes an oil-soluble bis(hydrocarbyl) phosphite ester and an oil-soluble hydrocarbyl substituted phenol wherein a specific weight ratio is maintained with respect to the phosphite and phenol. The patent indicates that the inclusion of these particular additive compounds in the particularly disclosed ratio provides enhanced elastomer compatibility to the fluid.
Published European Patent Application 113,199 published July 11, 1984, discloses a tractor hydraulic fluid which includes oleyl phosphite in a tractor antifriction hydraulic fluid as well as thioethyloctadecenylsuccinate containing tractor hydraulic fluids.
British Patent 1,452,513 dated Oct. 13, 1976, discloses lubricant compositions which include a fatty acid and a fatty acid amide in a wet braking system for tractors which was found to be useful in reducing the amount of noise over a wide temperature range.
British Patent 1,440,261 discloses a composition for reducing the noise in the wet braking systems of tractors. The fluid was comprised of a lubricant oil, and a detergent or dispersant mixed with stearic acid. The composition indicated that it also included alkylene polyamine dispersants, calcium and barium sulfonates and phenates, antiwear-antioxidants and oleic acid.